Patron Spells are provided to a Warlock as Spells Known, as opposed to Spells they may take.

The caveat here, is if a Warlock ends, or otherwise breaks their pact with their patron, they lose access to these spells until they find a new patron.

A bond with your patron is what allows you to grow as a Warlock. Breaking your Pact separates you from the mystic energy that allows you to grow. Many Patrons are capable of removing the seed of power, reverting you back into a common man, but such an entity needs to lie on the cusp of, or has otherwise reached Divinity. In most cases, the loss of a bond, your pact, simply prevents a Warlock from progressing in power, as the entity granting them knowledge is no longer doing so. In such a case, a Warlock would need to find a new entity to grant them their secrets.

 

Some patrons, may grant a new spark to a Warlock should a pact be complete. This tends to come without restriction, and will allow a Warlock to grow, without the superviision of the patron. In such cases, it may even be possible to ask favor from their former Patron, though this is seen as extremely rare.